This article examines the rapid expansion of the foreign national prison population in the UK against a backdrop of public and political anxiety about immigration and crime. It explores official data considering some of the possible explanations for the growth in the number of foreign national prisoners and the implications this has for penal management. Whilst increases in both the number of foreign nationals entering the UK and the number of foreign nationals in UK prisons has strengthened the association between immigration and crime in the public imagination, there is little empirical evidence to suggest that foreign nationals are more dangerous than British nationals. Instead, the growth of the foreign national prison population appears to stem from a number of sources that may operate alone or in tandem. (Published Abstract)